Abstract

Rationale: Asthma can coexist with chronic obstructive pulmonary disease (COPD), particularly in older adults, a condition labeled the overlap syndrome (OS). Additionally, while airway inflammation in COPD is generally neutrophilic, COPD patients may have features of asthma and thus a component of allergic airway inflammation. This study characterized allergic airway inflammation in patients with COPD using fractional exhaled nitric oxide (FeNO).

Methods: A single-visit, outpatient study in 191 subjects age 40 years and older with COPD or the overlap syndrome. All subjects performed spirometry and FeNO testing. Subjects were classified as have COPD/asthma, COPD or COPD/emphysema using ICD codes.

Results: The subjects had a mean age of 63.9 ± 11.3 years, a mean smoking history of 46 ± 29 pack years and a mean FEV1 % predicted of 53.9 ± 22.1%. A total of 32% of subjects were classified as mixed COPD/asthma, 42% as COPD and 26% as COPD/emphysema. The mean FeNO level for all subjects was 15.3 ± 17.2 ppb. FeNO level versus diagnosis are shown below.

Conclusions: These data indicate that increases in FeNO do occur in patients with COPD and increases in FeNO to intermediate or high levels occurred in 21 of 191 subjects (11%) in this study. Increases in FeNO were most common in subjects with mixed COPD/asthma. Since FeNO is useful for identifying patients with allergic airway inflammation who will have a beneficial response to treatment with an ICS, these data may have important implications for the management of COPD patients.